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Topic 4: Inorganic chemistry and the Periodic Table > Group 7, the halogens > Flashcards

Group 7, the halogens Flashcards

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1
Q

describe the physical appearance of the halogens
chlorine
bromine
iodine

A

chlorine -yellow green gas
bromine - dark red
iodine - dark grey solid

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2
Q

why do not we study fluorine and astatine in the lab ?
F
At

A

F - too dangerous
At - highly radioactive

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3
Q

write the balanced symbol equation for the reaction between magnesium and bromine

A

Mg (s) + Br2 (aq) -> MgBr2 (g)
- magnesium is oxidized
- bromine is reduced

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4
Q

write the ionic equation for the oxidation of iron(II) ions in solution to iron(III) ions by aqueous chlorine

A

2Fe2+ (aq) + CI2 (aq) -> 2Fe3+ (aq) + 2CI- (aq)

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5
Q

why cant iodine iron(II) ions compounds ?

A

only capable of oxidizing iron to the +2 oxidation state

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6
Q

reactions with non metals
- when heated with hydrogen
chlorine
bromines
iodine

A

chlorine - colorless acidic gas
bromine - pale blueish flame
iodine - reversible reaction

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7
Q

what is the test for halide ions

A
  1. place potassium chloride to a height of 1cm into a test tube
  2. add silver nitrate until precipitate forms
  3. add twice the volume of dilute ammonia, stopper and shake
  4. if the precipitate remains, add conc. ammonia in the fume cupboard and shake carefully
  5. repeat with potassium bromide and potassium iodide
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8
Q

colour of the precipitate with AgNO3
chloride
bromide
iodide

A

chloride - white
bromide - cream
iodide - yellow

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9
Q

solubility of these in dilute ammonia
chloride
bromide
iodide

A

chloride - ppt dissolves
bromide - ppt remains
iodide - ppts remains

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10
Q

state the observations and products of NaCI + conc. H2SO4

A

-colourless acidic gas forms that fumes in moist air (HCI)
-white solid remains (NaHSO4)

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11
Q

what type of reaction is NaCI + conc. H2SO4

A

acid base reaction so no redox

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12
Q

state the observations and products of NaBr + conc. H2SO4

A

-orange vapour (SO2) mixed with colourless acidic gas
-solid product is NaHSO4
-some HBr is formed

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13
Q

what type of reaction is NaBr + conc. H2SO4

A

redox reaction
- the bromide ions is oxidised to bromine and the sulphur is reduced from +6 to +4
- acid base reaction
-HBr forms

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14
Q

state the observations and products of NaI + conc. H2SO4

A
  • a dark solid forms which gives off a purple vapour on warming O2
  • some yellow solid may be seen and there is a bad egg smell
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15
Q

what type of reaction is NaI + conc. H2SO4

A

redox reaction
- iodide ions are oxidised to iodine and the sulphur is reduced from +6 to 0 -2

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16
Q

oxidising power - define

A

a measure of the strength with which an atom is able to attract and capture an electron

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17
Q

reducing power - define

A

a measure of the tendency of an atom or ion to donate an electron

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18
Q

list three properties the hydrogen halides have in common

A
  • strong acids so ionise completely
  • very soluble in water
  • colourless gases at room temperature which fume in moist air
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19
Q

write the balanced symbol equation for the reaction between ammonia and hydrogen chloride gas

A

NH3 (g) + HCI (aq) -> NH4CI (s)
- would would see white smoke

20
Q

making bleach - disproportionation reaction

A

CI2 (g) + 2OH (aq) -> CIO- (aq)+ CI- (aq) + H2O (l)

21
Q

what is the boiling point of halogens as we go down the group ?

A

increases bc the london forces increase due to the increasing size and relative mass of the atoms

22
Q

what is the physical state of group 7 at the top n bottom ?

A

gas at the top
solid at the bottom

23
Q

what is the electronegativity as you go down the halogens ?

A

decreases bc the atoms get larger and the distance between the positive nucleus and bonding electron increases - more shielding

24
Q

when undertaking halogen displacement reactions what can we add to see the colour change easily ?

A

organic solvent like hexane

25
Q

what form if the halogen present will dissolve readily in a displacement reaction ?

A

organic solvent above the aqueous layer - a coloured band will appear

26
Q

the more reactive halogens will displace in a more/less reactive halide ions ?

A

less

27
Q

as we go down the group is the halogens less/more oxidising ?

A

less

28
Q

what happens if addition of chlorine water (almost colourless) + potassium chloride solution (colourless) ?

A

no reaction

29
Q

what happens if addition of chlorine water (almost colourless) + potassium bromide solution (colourless) ?

A

Aq - yellow
Org - orange

30
Q

what happens if addition of chlorine water (almost colourless) + potassium iodide solution (colourless) ?

A

Aq - brown
Org - purple

31
Q

what happens if addition of bromine water (almost colourless) + potassium chloride solution (colourless) ?

A

no reaction
Aq - yellow
Org - orange

32
Q

what happens if addition of bromide water (almost colourless) + potassium bromide solution (colourless) ?

A

no reaction
Aq - yellow
Org - orange

33
Q

what happens if addition of bromine water (almost colourless) + potassium iodide solution (colourless) ?

A

Aq - brown
Org - purple

34
Q

what happens if addition of iodide water (almost colourless) + potassium chloride solution (colourless) ?

A

no reaction
Aq - brown
Org - purple

35
Q

what happens if addition of iodide water (almost colourless) + potassium bromide solution (colourless) ?

A

no reaction
Aq - brown
Org - purple

36
Q

what happens if addition of iodide water (almost colourless) + potassium iodide solution (colourless) ?

A

no reaction
Aq - brown
Org - purple

37
Q

what are the uses of sodium chlorate ?

A

treating water
bleaching paper and fabrics
cleaning agents

38
Q

what does chlorine do when added to water ?

A

kill bacteria

39
Q

water sterilisation - chlorine

A

H2O + CI2 <-> HCI + HCIO
- chlorine has been simultaneously reduced and oxidised

40
Q

why is I- more powerful reducing agent than F- ?

A

the outer electron is lost more readily

41
Q

what does hydrogen halides form when dissolved in water ?

A

acidic solutions

42
Q

when hydrogen halides react with water in the air what does it form ?

A

white misty fumes

43
Q

test for ammonium compounds

A

add sodium hydroxide gently heat, and if ammonium compounds gas will be produced

44
Q

test for hydroxides

A

hydroxides are alkaline and they will turn red litmus blue

45
Q

why is HCI a good conductor of electricity ?

A

the covalent bond in hydrogen chloride changes to ionic bond in aqueous solutions

Topic 4: Inorganic chemistry and the Periodic Table (4 decks)

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